Add built-in userlock manipulation functions to replace the former

contrib functionality.  Along the way, remove the USER_LOCKS configuration
symbol, since it no longer makes any sense to try to compile that out.
No user documentation yet ... mmoncure has promised to write some.
Thanks to Abhijit Menon-Sen for creating a first draft to work from.

1 files changed, 257 insertions, 3 deletions

diff --git a/src/backend/utils/adt/lockfuncs.c b/src/backend/utils/adt/lockfuncs.c
index 40046a020a0..f7c7deca8d9 100644
--- a/src/backend/utils/adt/lockfuncs.c
+++ b/src/backend/utils/adt/lockfuncs.c
@@ -1,20 +1,21 @@
 /*-------------------------------------------------------------------------
  *
  * lockfuncs.c
- *		Set-returning functions to view the state of locks within the DB.
+ *		Functions for SQL access to various lock-manager capabilities.
  *
  * Copyright (c) 2002-2006, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
- *		$PostgreSQL: pgsql/src/backend/utils/adt/lockfuncs.c,v 1.24 2006/07/23 23:08:46 tgl Exp $
+ *		$PostgreSQL: pgsql/src/backend/utils/adt/lockfuncs.c,v 1.25 2006/09/18 22:40:37 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
 #include "postgres.h"
 
-#include "funcapi.h"
 #include "access/heapam.h"
 #include "catalog/pg_type.h"
+#include "funcapi.h"
+#include "miscadmin.h"
 #include "storage/proc.h"
 #include "utils/builtins.h"
 
@@ -266,3 +267,256 @@ pg_lock_status(PG_FUNCTION_ARGS)
 
 	SRF_RETURN_DONE(funcctx);
 }
+
+
+/*
+ * Functions for manipulating USERLOCK locks
+ *
+ * We make use of the locktag fields as follows:
+ *
+ *	field1: MyDatabaseId ... ensures locks are local to each database
+ *	field2: first of 2 int4 keys, or high-order half of an int8 key
+ *	field3: second of 2 int4 keys, or low-order half of an int8 key
+ *	field4: 1 if using an int8 key, 2 if using 2 int4 keys
+ */
+#define SET_LOCKTAG_INT64(tag, key64) \
+	SET_LOCKTAG_USERLOCK(tag, \
+						 MyDatabaseId, \
+						 (uint32) ((key64) >> 32), \
+						 (uint32) (key64), \
+						 1)
+#define SET_LOCKTAG_INT32(tag, key1, key2) \
+	SET_LOCKTAG_USERLOCK(tag, MyDatabaseId, key1, key2, 2)
+
+/*
+ * pg_advisory_lock(int8) - acquire exclusive lock on an int8 key
+ */
+Datum
+pg_advisory_lock_int8(PG_FUNCTION_ARGS)
+{
+	int64		key = PG_GETARG_INT64(0);
+	LOCKTAG		tag;
+
+	SET_LOCKTAG_INT64(tag, key);
+
+	(void) LockAcquire(&tag, ExclusiveLock, true, false);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * pg_advisory_lock_shared(int8) - acquire share lock on an int8 key
+ */
+Datum
+pg_advisory_lock_shared_int8(PG_FUNCTION_ARGS)
+{
+	int64		key = PG_GETARG_INT64(0);
+	LOCKTAG		tag;
+
+	SET_LOCKTAG_INT64(tag, key);
+
+	(void) LockAcquire(&tag, ShareLock, true, false);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * pg_try_advisory_lock(int8) - acquire exclusive lock on an int8 key, no wait
+ *
+ * Returns true if successful, false if lock not available
+ */
+Datum
+pg_try_advisory_lock_int8(PG_FUNCTION_ARGS)
+{
+	int64		key = PG_GETARG_INT64(0);
+	LOCKTAG		tag;
+	LockAcquireResult res;
+
+	SET_LOCKTAG_INT64(tag, key);
+
+	res = LockAcquire(&tag, ExclusiveLock, true, true);
+
+	PG_RETURN_BOOL(res != LOCKACQUIRE_NOT_AVAIL);
+}
+
+/*
+ * pg_try_advisory_lock_shared(int8) - acquire share lock on an int8 key, no wait
+ *
+ * Returns true if successful, false if lock not available
+ */
+Datum
+pg_try_advisory_lock_shared_int8(PG_FUNCTION_ARGS)
+{
+	int64		key = PG_GETARG_INT64(0);
+	LOCKTAG		tag;
+	LockAcquireResult res;
+
+	SET_LOCKTAG_INT64(tag, key);
+
+	res = LockAcquire(&tag, ShareLock, true, true);
+
+	PG_RETURN_BOOL(res != LOCKACQUIRE_NOT_AVAIL);
+}
+
+/*
+ * pg_advisory_unlock(int8) - release exclusive lock on an int8 key 
+ *
+ * Returns true if successful, false if lock was not held
+*/
+Datum
+pg_advisory_unlock_int8(PG_FUNCTION_ARGS)
+{
+	int64		key = PG_GETARG_INT64(0);
+	LOCKTAG		tag;
+	bool		res;
+
+	SET_LOCKTAG_INT64(tag, key);
+
+	res = LockRelease(&tag, ExclusiveLock, true);
+
+	PG_RETURN_BOOL(res);
+}
+
+/*
+ * pg_advisory_unlock_shared(int8) - release share lock on an int8 key
+ *
+ * Returns true if successful, false if lock was not held
+ */
+Datum
+pg_advisory_unlock_shared_int8(PG_FUNCTION_ARGS)
+{
+	int64		key = PG_GETARG_INT64(0);
+	LOCKTAG		tag;
+	bool		res;
+
+	SET_LOCKTAG_INT64(tag, key);
+
+	res = LockRelease(&tag, ShareLock, true);
+
+	PG_RETURN_BOOL(res);
+}
+
+/*
+ * pg_advisory_lock(int4, int4) - acquire exclusive lock on 2 int4 keys
+ */
+Datum
+pg_advisory_lock_int4(PG_FUNCTION_ARGS)
+{
+	int32		key1 = PG_GETARG_INT32(0);
+	int32		key2 = PG_GETARG_INT32(1);
+	LOCKTAG		tag;
+
+	SET_LOCKTAG_INT32(tag, key1, key2);
+
+	(void) LockAcquire(&tag, ExclusiveLock, true, false);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * pg_advisory_lock_shared(int4, int4) - acquire share lock on 2 int4 keys
+ */
+Datum
+pg_advisory_lock_shared_int4(PG_FUNCTION_ARGS)
+{
+	int32		key1 = PG_GETARG_INT32(0);
+	int32		key2 = PG_GETARG_INT32(1);
+	LOCKTAG		tag;
+
+	SET_LOCKTAG_INT32(tag, key1, key2);
+
+	(void) LockAcquire(&tag, ShareLock, true, false);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * pg_try_advisory_lock(int4, int4) - acquire exclusive lock on 2 int4 keys, no wait
+ *
+ * Returns true if successful, false if lock not available
+ */
+Datum
+pg_try_advisory_lock_int4(PG_FUNCTION_ARGS)
+{
+	int32		key1 = PG_GETARG_INT32(0);
+	int32		key2 = PG_GETARG_INT32(1);
+	LOCKTAG		tag;
+	LockAcquireResult res;
+
+	SET_LOCKTAG_INT32(tag, key1, key2);
+
+	res = LockAcquire(&tag, ExclusiveLock, true, true);
+
+	PG_RETURN_BOOL(res != LOCKACQUIRE_NOT_AVAIL);
+}
+
+/*
+ * pg_try_advisory_lock_shared(int4, int4) - acquire share lock on 2 int4 keys, no wait
+ *
+ * Returns true if successful, false if lock not available
+ */
+Datum
+pg_try_advisory_lock_shared_int4(PG_FUNCTION_ARGS)
+{
+	int32		key1 = PG_GETARG_INT32(0);
+	int32		key2 = PG_GETARG_INT32(1);
+	LOCKTAG		tag;
+	LockAcquireResult res;
+
+	SET_LOCKTAG_INT32(tag, key1, key2);
+
+	res = LockAcquire(&tag, ShareLock, true, true);
+
+	PG_RETURN_BOOL(res != LOCKACQUIRE_NOT_AVAIL);
+}
+
+/*
+ * pg_advisory_unlock(int4, int4) - release exclusive lock on 2 int4 keys 
+ *
+ * Returns true if successful, false if lock was not held
+*/
+Datum
+pg_advisory_unlock_int4(PG_FUNCTION_ARGS)
+{
+	int32		key1 = PG_GETARG_INT32(0);
+	int32		key2 = PG_GETARG_INT32(1);
+	LOCKTAG		tag;
+	bool		res;
+
+	SET_LOCKTAG_INT32(tag, key1, key2);
+
+	res = LockRelease(&tag, ExclusiveLock, true);
+
+	PG_RETURN_BOOL(res);
+}
+
+/*
+ * pg_advisory_unlock_shared(int4, int4) - release share lock on 2 int4 keys
+ *
+ * Returns true if successful, false if lock was not held
+ */
+Datum
+pg_advisory_unlock_shared_int4(PG_FUNCTION_ARGS)
+{
+	int32		key1 = PG_GETARG_INT32(0);
+	int32		key2 = PG_GETARG_INT32(1);
+	LOCKTAG		tag;
+	bool		res;
+
+	SET_LOCKTAG_INT32(tag, key1, key2);
+
+	res = LockRelease(&tag, ShareLock, true);
+
+	PG_RETURN_BOOL(res);
+}
+
+/*
+ * pg_advisory_unlock_all() - release all userlocks
+ */
+Datum
+pg_advisory_unlock_all(PG_FUNCTION_ARGS)
+{
+	LockReleaseAll(USER_LOCKMETHOD, true);
+
+	PG_RETURN_VOID();
+}